Flexible tip medical instrument

ABSTRACT

A needle set includes a hollow outer needle and an inner needle slidably disposed within the lumen of the outer needle. The outer needle defines a first relief notch having a length that is longer than its width. The inner needle defines a second relief notch, which is also longer than wide. The needle set has a first position with the first relief notch superposed over the second relief notch. A slot may also be defined in the outer needle. A firing mechanism may be engaged to the proximal ends of the needles to move the needles relative to one another. The needle set may be used with an elongated introducer cannula having a curved portion with the outer and inner needles being sufficiently flexible to traverse the curved portion without binding between the needles.

This application is a continuation of International ApplicationPCT/US01/44388 filed Nov. 28, 2001, which is a continuation ofapplication Ser. No. 09/723,845, filed on Nov. 28, 2000, now U.S. Pat.No. 6,419,641.

FIELD OF THE INVENTION

The present invention relates generally to biopsy systems. Specifically,the invention concerns devices for obtaining biopsy samples throughveins and arteries.

BACKGROUND OF THE INVENTION

In the practice of diagnostic medicine, it is often necessary ordesirable to perform a biopsy, or to sample selected tissue from aliving patient for medical evaluation. Cytological and histologicalstudies of the biopsy sample can then be performed as an aid to thediagnosis and treatment of disease. Biopsies can be useful in diagnosingand treating various forms of cancer, as well as other diseases in whicha localized area of affected tissue can be identified.

During the biopsy procedure, care is taken to minimize the physicaltrauma inflicted upon the intervening tissues that surround the affectedarea or target tissue and at the same time to protect the practitionerfrom health hazards. One typical biopsy procedure includes inserting ahollow biopsy needle through the intervening tissue into the targettissue to be sampled. The sample tissue is then harvested through theneedle by applying suction through the needle, typically with a syringe.

Special considerations apply if the biopsy is to be performed on aninternal organ deep within the body such as the liver. Previously,obtaining a tissue sample from an internal organ, such as the liver, wascarried out percutaneously by entering the skin in the vicinity of theorgan and thereafter extracting a core of liver material through thebiopsy needle. This method, although effective in obtaining an adequateamount of tissue from the liver, is no longer acceptable practice, sinceit is not uncommon for the patient to suffer from serious healthcomplications caused by the biopsy. For example, patients generallyexperience extreme pain, and additionally, the liver profusely bleedsafter percutaneous biopsy. Moreover, liver biopsies are typicallyperformed on patients having liver disease, liver transplants andcoagulation disorders, and such conditions further complicatepercutaneous liver biopsies.

Alternatively, tissue samples may be obtained without the problemsassociated with percutaneous biopsy by accessing the liver via atransjugular procedure. Known techniques involve accessing the liverthrough the jugular vein with an elongated biopsy device. Typically,these biopsy devices are identical to typical single and double actionbiopsy devices except that the inner and outer needles are elongated toaccess the liver from the jugular vein.

An example of a typical transjugular single action biopsy device 20 isshown in FIGS. 1–3. Biopsy device 20 includes an outer hollow needle 22defining a lumen 24 therethrough. An inner needle 26 is slidinglyengaged inside lumen 24 and is moveable relative to outer needle 22. Theinner needle 26 defines a first or distal end 28 having a tissue cuttingpoint 30 and a cavity 32 adjacent first end 28 for receiving tissuesamples. The inner needle 26 is slidable relative to outer needle 22between a first retracted position (FIG. 3) and a second extendedposition (FIG. 2). In the first retracted position, inner needle 26 isretracted within lumen 22 so that outer needle 22 covers cavity 32 sothat the distal end can be inserted into the liver. In the secondextended position, the first end 28 of inner needle 26 is extended awayfrom outer needle 22 to expose cavity 32 to tissues at the biopsy site.Such means are known in the art and commercially available. For example,biopsy devices of this type are available form U.S. Biopsy, Inc., adivision of Promex, Inc., 3049 Hudson Street, Franklin, Ind., (317)736-0128.

During a transjugular liver biopsy an elongated introducer 34, asillustrated in FIG. 4, is inserted through a small incision or puncturemade in the skin. The introducer 34 is an elongated, small diametercannula defining a lumen 36 that receives and guides the distal end 35of biopsy device 20 to the biopsy site. A tip 38 of the introducer 34 iscarefully advanced through venous passageways with the assistance ofX-ray or fluoroscopy. Great care is taken to position the tip 38 at theprecise location of the intended biopsy site. The biopsy device 20 isthen advanced through the introducer lumen 36 and thereafter tissuecutting point 30 of inner needle 26 enters the liver tissue. During thisinsertion stage of the procedure, inner needle 26 is positioned withinouter needle 22 in the first, retracted position (FIG. 3).

Once device 20 has been positioned at the targeted site for the biopsy,inner needle 26 is momentarily driven into liver tissue far enough toexpose cavity 32 of inner needle 26. Liver tissue then prolapses intocavity 32. The device is then fired to advance outer needle 22 alonginner needle 26 to cover cavity 32. This forward movement of outerneedle 22 severs the prolapsed tissue to obtain a tissue sample, whichbecomes trapped in cavity 32 of inner needle 26. Movement of inner andouter needles 26, 22 to capture a sample occur almost instantaneouslyvia firing mechanism 27 engaged with proximal ends 29 of needles 26, 22.The quality of the sample is largely dependent on the thrust or “strike”of outer needle 22 securing the tissue since the tissue is oftenparenchymatous tissue and is gelatinous in consistency. With outerneedle 22 blocking the opening of cavity 32, biopsy assembly 20 may thenbe withdrawn, carefully backing out of introducer 34 leaving theintroducer in place. Biopsy device 20 is then withdrawn from the targetsite carrying the sample within cavity 32. To collect the biopsy sampleouter needle 22 is once again retracted to expose cavity 32 of innerneedle 26. Typically, the biopsy device is re-inserted into theintroducer to collect another biopsy sample. The procedure may berepeated several more times until satisfactory samples have beenobtained.

A problem associated with this type of biopsy device is that the rigidinner and outer needles 26, 22 are metallic, commonly stainless steel,and lack the flexibility to freely move within the introducer 34 due tothe significant curve 42 located at the introducer's distal end 44 (FIG.4). The curve 42 of the introducer 34 causes the inner and outer needle26, 22 to bind with an inner wall 46 comprising lumen 36 of theintroducer 34, which in turn, can cause movement of the introducer.Consequently, the introducer is prone to movement due to the formationof resistance between inner and outer needles 26, 22 traversing curve 42in introducer 34. Movement of the introducer once it is ideally placedis undesirable since damage to the surrounding tissue and poor biopsysamples are frequently the result of such movement. Moreover, since thecurve 42 in the introducer causes continuous binding, even after theouter needle 22 has cleared the curve 42, much of the momentum impartedon inner and outer needles 26, 22 via spring force of firing mechanism27 is utilized to overcome this binding or frictional force.Consequently, the effectiveness of the firing mechanism 27 is diminishedresulting in recovery of small and fractured tissue specimens. Moreover,repeatedly firing the biopsy device 20 during subsequent sampling eventscauses the sliding surfaces of the outer needle 22 and inner wall 46 ofintroducer 34 to become “galled” i.e., deformation of the slidingsurfaces, resulting in an additional and significant decrease inperformance of the firing mechanism 27. As a result, little if anytissue is recovered and the device 20 may be permanently damaged beforean adequate specimen is captured. The damaged device is then discardedand additional devices must then be used to capture adequate andsufficient tissue. This is unfortunately common and leads to asignificant and unwarranted cost increase due to equipment, personneland room charges, as well as an extended biopsy procedure for thepatient.

Biopsy of an organ deep within the body, such as the liver, requires theintroducer tip to be implanted a significant dept. Since the quality ofthe specimen is largely dependent on the striking momentum of the biopsydevice over this long distance, a large degree of stiffness of theneedles is necessary to transmit striking force from the firing deviceto the tip of the coring needles. Unfortunately, the needles tend tobind with the lumen walls of the long introducer at the bend. Thus, whatis needed is a needle assembly that provides flexibility withoutcompromising the stiffness and integrity of the needles.

U.S. Pat. No. 4,907,598 to Bauer discloses an alternative to rigid innerand outer needle assemblies by employing a flexible cannula and wireassembly that flexes as the curve in the introducer is traversed. Thewire, comprised of a cable, and the cannula, provided with a stackedcoil arrangement are designed to enhance flexibility. Problematically,the flexible cable and cannula assembly are generally flaccid indisposition providing a biopsy tip, located at the distal end of thecable and cannula assembly, that is unwieldily and uncontrollable.Moreover, a significant amount of energy of the firing device is lost bythe flexible cannula and wire assembly as it yields when the firingdevice is activated. Consequently, small and fragmented specimens arecaptured and multiple additional firings are generally required.

U.S. Pat. No. 5,620,415 to Lucey et al. discloses a surgical deviceconstructed to transmit forces applied at a handpiece through a bendregion of a rigid outer tube. Force is transmitted from the handpiece toa cutting tool through a pair of internested tubes supported within therigid tube. The assembly provides a flexible region caused by the innertube having a series of circumferential slots that lie completely withinthe bend region at the time the handpiece is operated. In addition, thecircumferential slots are parallel to each other and extend fromopposite sides of the inner tube to form an accordion-like design. Thesecircumferential slots provide a limited measure of binding relief at thebend, however an unsatisfactory level of relief for deep internal organbiopsy. In addition, these slots result in a loss of axial strength, andultimately, a loss in precision between the stationary tube and theinner movable tube. As an added disadvantage, it is very expensive toproduce the accordion-like design of these slots.

U.S. Pat. No. 5,911,701 to Miller and Ireland discloses a surgicalcutting instrument having a curved outer cannula which slidably supportsa cutting member disposed therein. The cutting member is attached to acontinuous tubular member consisting of a rigid portion affixed to aflexible body portion extending along the curve of the outer cannula. Toensure a propitious measure of axial rigidity in the flexible bodyportion a plurality of driving cables are provided within the flexiblebody portion. Although the device is flexible, it is a motorizedsurgical cutting device, and the degree of complexity introduced by theconcept is not desirable in the single and double action biopsy devicesused for intravascular accessed biopsy procedures.

A need has remained for a transjugular biopsy device that overcomes theresultant binding force imparted by the introducer on the needle coringassembly. Additionally, what is needed is a transjugular biopsy deviceamenable to repeated uses without a measurable degradation inperformance. Further, an inexpensive biopsy device that may berepeatedly fired without damage to the device would be desirable.

SUMMARY OF THE INVENTION

Accordingly, the present invention overcomes the disadvantages of priorbiopsy devices by providing a biopsy device having a flexible distalportion for obtaining a biopsy sample from a biopsy site. The devicesinclude a coring cannula having a wall between a proximal end and adistal end and defining a lumen therebetween. A wire is slidablydisposable within the lumen of the coring cannula and defines a samplingcavity adjacent the distal end and a wire relief notch adjacent thesampling cavity. A firing mechanism is engaged to the proximal ends ofthe coring cannula and the wire. The firing mechanism is operable tomove the coring cannula relative to the wire from the second position tothe first position to trap tissue from the biopsy site in the samplingcavity. The wire is slidable relative to the coring cannula between afirst position retracted within the lumen so that the coring cannulacovers the sampling cavity and a second position wherein the distal endof the wire is extended away from the coring cannula to expose thecavity to tissue in the biopsy site. The wall defines a coring reliefnotch adjacent the distal end and has a length along a longitudinal axisof the cannula longer than a diameter of the coring cannula. The wirerelief notch has a length along a longitudinal axis of the wire longerthan a diameter of the wire.

Another aspect of the invention provides a biopsy assembly including anintroducer having an elongated cannula defining an introducer lumenbetween a proximal end and a distal end. The cannula has a curvedportion adjacent the distal end. A body portion is attached to theproximal end of the cannula and defines a channel in communication withthe introducer lumen. An access port is defined in the body portion incommunication with the channel. A biopsy device of this invention isdisposable within the introducer lumen through the access port. Thedistal end of the biopsy device is extendable out through the distal endof the introducer cannula to access tissue.

One object of the invention is to provide biopsy devices and assembliesspecifically designed for accessing and performing a biopsy on aninternal organ situated deep within a body. One advantage of the presentinvention is that it can be achieved through inexpensive modificationsof existing devices. Yet another advantage of the present invention isits capability to yield a sufficient amount of biopsy samples using asingle device. Yet another advantage is that the present invention doesnot require complicated cabling or the attachment or welding of similaror dissimilar materials to comprise the flexible portions. These andother objects, advantages and features are accomplished according to thedevices, assemblies and methods of the present invention.

DESCRIPTION OF THE FIGURES

FIG. 1 is plan view of a prior art biopsy device;

FIG. 2 is an enlarged fragmentary view of FIG. 1 showing detail of thetip with the device in an extended position;

FIG. 3 is an enlarged fragmentary view of FIG. 1 showing detail of thetip with the device in a retracted position;

FIG. 4 is a plan view of the introducer of the biopsy assembly of FIG.5;

FIG. 5 is a plan view of a first embodiment biopsy assembly according topresent invention;

FIG. 6 is an enlarged fragmentary view of the biopsy assembly of FIG. 5,showing the body portion of the introducer in section;

FIG. 7 is a plan view of the biopsy assembly of FIG. 5 showing theintroducer removed;

FIG. 8 is an enlarged plan view of the biopsy device of FIG. 7 depictingthe distal end of the biopsy device in a position wherein the coringcannula is retracted (pre firing);

FIG. 9 is an enlarged plan view of the biopsy device of FIG. 7 depictingthe distal end of the biopsy device in a position wherein the coringcannula is extended (post firing);

FIG. 10 is a sectional view of the biopsy device of FIG. 9 taken alongline 10—10, depicting the wire relief notch and the coring relief notch;

FIG. 11 is a sectional view of the biopsy device of FIG. 9 taken alongline 11—11, depicting one of the discrete slots and the sampling cavity;

FIG. 12 is a sectional view of the biopsy assembly of FIG. 16 takenalong line 12—12, depicting the wire relief notch interacting with thecoring relief notch within the curve of the introducer;

FIG. 13 is a sectional view of the biopsy device of FIG. 8 taken alongline 13—13, depicting the sampling cavity;

FIG. 14 is an enlarged fragmentary view of the distal end of the biopsyassembly of FIG. 5, partially in section, illustrating the cannulaflexing at the bend of the introducer;

FIG. 15 is an exploded view of the biopsy assembly of FIG. 7;

FIG. 16 is an enlarged fragmentary view of the distal end of the biopsyassembly of FIG. 5, partially in section, illustrating the cannula andwire flexing at the bend of the introducer;

FIG. 17 is an enlarged fragmentary view of the tip of a biopsy deviceaccording to the present invention showing an alternative wire tipconfiguration;

FIG. 18 is an end view of the biopsy device of FIG. 5, viewed along theline 18—18 of FIG. 5;

FIG. 19 is a plan view of a second embodiment of a biopsy deviceaccording to the present invention with the introducer removed;

FIG. 20 is an enlarged fragmentary view of the biopsy device of FIG. 19,illustrating the distal end; and

FIG. 21 is a diagrammatical view of the liver and venous system.

Corresponding reference characters indicate corresponding partsthroughout the several views. Although the drawings represent anembodiment of the present invention, the drawings are not necessarily toscale and certain features may be exaggerated in order to betterillustrate and explain the present invention. The exemplification setout herein illustrates an embodiment of the invention, in one form, andsuch exemplifications are not to be construed as limiting the scope ofthe invention in any manner.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

For the purposes of promoting an understanding of the principles of theinvention, reference will now be made to the embodiments illustrated inthe drawings and specific language will be used to describe the same. Itwill nevertheless be understood that no limitation of the scope of theinvention is thereby intended. The invention includes any alterationsand further modifications in the illustrated devices and describedmethods and further applications of the principles of the invention thatwould normally occur to one skilled in the art to which the inventionrelates.

The present invention provides devices and assemblies to access aninternal organ through a patient's venous and arterial system to obtaina tissue specimen from the target organ. A long narrow tube orintroducer cannula is precisely placed through interconnecting veins andarteries along a tortuous path. Previously used coring needle assembliesexhibited pronounced binding with the introducer cannula as the curvesof the introducer were traversed. To overcome this binding, the presentinvention provides a needle coring assembly including a flexible tiphaving precisely placed relief notches and relief slots disposed in thecoring wire and the coring cannula. Although features of the presentinvention allow the coring needle assembly to flex as it confrontscurves in the introducer, the strength, durability and function of theassembly are not compromised.

A biopsy assembly 50 according to one embodiment of this invention isshown in FIG. 5. The assembly 50 includes an introducer 34 and a biopsydevice 52. The preferred introducers of this invention are availablefrom Cook, Inc. of Bloomington, Ind. FIGS. 4 and 6 illustrate introducer34, which is provided with an elongated cannula 54 defining anintroducer lumen 36 between a proximal end 56 and a distal end 44. Lumen36 terminates at an opening 39 defined in distal end 44. In thisembodiment, cannula 54 has a curved portion 42 adjacent the distal end44 to navigate the sharp angle at the union of the vena cava and hepaticveins. In other embodiments, the cannula 54 may have other curvedportions or be flexible to accommodate the tortuous path along thevenous system to an organ of the body. The biopsy devices of thisinvention will then have flexible regions that correspond to such othercurved or flexible portions of the cannula. The cannula 54 is preferablyabout 60 cm long and includes an inside diameter slightly larger thanbiopsy device advanced into lumen 36.

Introducer 34 further includes a body portion 58 attached to theproximal end 56 of the cannula 54. Body portion 58 defines a channel 60in communication with the introducer lumen 36. The body portion 58includes an access port 66 for the insertion of coring cannula 68 withinthe body portion 58 which is in communication with the channel 60. Theaccess port includes a connector valve 62 for sealingly receiving abiopsy needle. In a preferred embodiment, valve 62 includes a siliconedisk 64 for preventing the backflow of fluids passing along the biopsydevice 52 at the site of the disk 64. In a specific embodiment, bodyportion also includes connector 70 to which polyvinyl tube 72 and Luerlock connector 74 are connected for introducing and aspirating fluidsthrough introducer 34 as is required. Introducer 34 further includessheath 75 snugly engaged to the exterior of the entire length of cannula54 and attached to a proximal end 56 thereof through an additional Luerlock 77. Sheath 75 is constructed from a low friction material such as aPTFE or a Nylon composite, so designated, to protect the intima asintroducer 34 is advanced through the veins and arteries.

Assembly 50 further includes biopsy device 52, which is disposablewithin the introducer lumen 36 through the access port 66. One firstembodiment of a biopsy device 52 is shown in FIGS. 7–13 and includescoring cannula 68 and a wire 76, which are both flexible at their distalends 78, 80 for traversing the curved portion 42 in introducer 34 as thebiopsy device 52 is inserted into the introducer lumen 36. Wire 76 ispreferably a solid, non-cannulated wire. In embodiments in which theintroducer is flexible or has a curved portion in another or additionallocations, the biopsy devices of this invention will have flexibleportions that correspond to the curved or flexible portions of theintroducer.

Coring cannula 68 includes a wall 82 (FIG. 10) between a proximal end 84and a distal end 78 and defines a lumen 86 therebetween. The wall 82defines an elongated coring relief notch 88 adjacent the distal end 78.As best shown in FIG. 7, the coring relief notch 88 extends along alongitudinal axis 90 of the cannula 68. The length lc of the coringrelief notch 88 is longer than the width Wc (FIG. 10) of notch 88. Inone specific embodiment, length lc is about 2.0″, for example. In theexemplary embodiment, coring cannula 68 is made of stainless steeltubing from between 16 to 20 gage, for example.

Distal end 78 of coring cannula 68, the details of which are best shownin FIGS. 8–9 and 14–16, includes a pair of discrete slots 92 and 94.Each slot 92, 94 extends radially into wall 82 of cannula 68 and flexingportions 96, 98, are adjacently positioned relative to slots 92, 94. Inone specific embodiment, discrete slots 92, 94 extend radially adistance of three-fourths the outer diameter D_(c) of the coring cannula68 and have respective widths of 0.020″, for example. Referring now toFIGS. 11 and 14, as tip 100 of coring cannula 68 traverses curve 42 inintroducer 34, each discrete slot 92, 94 allows cannula 68 totemporarily flex reducing sliding resistance between outer surface 102of cannula 68 and inside surface 46 of introducer 34. Further, flexingportions 96, 98 are sized to allow flexibility in coring cannula 68 yetare structured and arranged to prevent permanent deformation of theflexing portions. In this specific embodiment, the coring cannuladefines two discrete slots. However, any number of slots is contemplateddepending on the degree and locations where flexibility is required.

Coring relief notch 88 extends partially through wall 82 of coringcannula 68. In contrast to radially formed discrete slots 92, 94 incoring cannula 68, notch 88 extends along longitudinal axis 90 of coringcannula 68 a substantial distance, such as 2.0″, as in one specificembodiment for example. Coring relief notch 88 may measure a depth ofthree fourths of the outer diameter D_(c) of cannula 68, for example.Referring to FIG. 9, a first end 104 of notch 88 is positionedapproximately 0.60″ from furthest extent of tip 100 in one specificembodiment.

Biopsy device 52 includes wire 76 slidably disposable within the lumen86 of the coring cannula 68 and is provided with a proximal end 108 anddistal end 80. A sampling cavity 110 positioned adjacent the distal end80. Wire 76 further defines a wire relief notch 112, which is adjacentthe sampling cavity 110 in this embodiment. Wire relief notch 112extends along a longitudinal axis of the wire that is coincident withthe longitudinal axis 90 of the cannula 68. The length lw (FIG. 15) ofnotch 112 is longer than the width Ww (FIG. 10) of notch 112. In onespecific embodiment, lw is about 2.0″, for example. As best seen inFIGS. 14 and 16, in this particular embodiment wire 76 includes a trocartip 115 which is angled to a point as is customary to expedientlypuncture the liver with little or no resistance from the liver tissue.As an alternative to tip 115, tip 116 as illustrated in FIG. 17,includes an angled tip 116, the angle closely tracking the angle ofcannula tip 100, to reduce the risk of tip 116 binding with introducer34 as it traverses curve 42. Yet another alternative to tips 115 and 116is tip 114, as best illustrated in FIG. 9. Tip 114 of wire 76 is angledopposite to that of tip 100 of cannula 68.

Referring now to FIGS. 9 and 10, coring relief notch 88 in coringcannula 68 substantially superposes wire relief notch 112 in wire 76 toprovide a substantial degree of flexibility to both cannula 68 and wire76 at the site of curve 42. FIGS. 14 and 16 detail the progression ofdistal end 78 of coring cannula 68 traversing curve 42 in introducer 34(FIG. 14), followed by flexible wall portions 118, 120 of coring cannula68 and wire 76, respectively, traversing curve 42 in introducer 34 (FIG.16). In contrast to the prior art coring cannula 22 (outer needle) andwire 26 (inner needle), shown in FIGS. 1 and 2, a gap 122 is providedbetween coring cannula 68 and wire 76 to allow coring cannula 68 andwire 76 to flex as curve 42 is traversed. This flexibility significantlyreduces binding between cannula 68 and wire 76. Since gap 122 extends asignificant distance along the length of coring cannula 68 and wire 76at the site of curve 42, cannula 68 and wire 76 remain flexible over theentire throw of the firing device 124. As a consequence, the energyutilized by firing device 124 to advance coring cannula 68 is notadversely affected since there is little or no increase in resistancebetween coring cannula 68 and wire 76 due to the curve 42.

It is envisioned that as little as one relief or as many as severalreliefs may be provided in the cannula such that a significant reductionof resistance is experienced as the cannula 68 traverses curve 42 inintroducer 34. However, providing an over abundance of reliefs ispreferably avoided since stiffness of the cannula and stylet assemblymay be compromised. It is further envisioned that multiple reliefs maybe placed at varying positions along the cannula to facilitate reducedresistance between the cannula and an introducer having multiple bendsalong its length.

FIGS. 10 and 11 detail the relationship between coring relief notch 90and discrete slot 94. Coring relief notch 88 of cannula 68 is arrangedsubstantially symmetrical respective of reference axis Y. Axis Ycorresponds to a zero degree reference and it may be seen that cannulawall 82 is provided between approximately −45 and 45 degrees relative tothe Y axis (FIG. 10). Similarly, discrete slot 94 (FIG. 11) issymmetrical relative to reference axis Y and therefore coring reliefnotch 88 and discrete slot 94 are axially aligned. In other words,coring relief notch 88 and discrete slot 94 are circumferentiallyaligned relative to one another. In the preferred embodiment, discreteslot 92 is provided with a substantially identical structure andorientation as discrete slot 94.

FIGS. 12 and 16 show the interaction between wire relief notch 112 andcoring relief notch 88 at a position within the introducer 34corresponding to firing device 124 being activated. Notably, the onlyportion of biopsy device 52 located at curve 42 upon activation offiring device 124 is flexible wall portion 118 of cannula 68 andflexible wall portion 120 of wire 76. Therefore, these two portions flexat the site of curve 42 and as a result little or no friction isregistered at the curve during activation of the firing device 124.Moreover, since inner wall 46 of introducer 34 is slightly larger thanthe outer diameter D_(c) of cannula 68, the introducer 34 providessupport to flexible wall portions 118 and 120 of cannula 68 and wire 76,respectively.

FIGS. 8 and 13 best illustrate the sampling cavity 110. Wire reliefnotch 112 of wire 76 is arranged substantially symmetrical respective ofreference axis Y. Flexible wall portion 120 of wire 76 is providedbetween approximately −135 and 135 degrees relative to the Y axis.Similarly, sampling cavity 110 is symmetrical relative to reference axisY and therefore wire relief notch 112 and sampling cavity 110 areaxially aligned.

Wire 76 is slidable relative to the coring cannula 68 between a firstretracted position (FIG. 9) within the lumen 86 with the coring cannula68 covering the sampling cavity 110 and a second, extended position(FIG. 8) wherein the distal end 80 of the wire 76 is extended away fromthe coring cannula 68 to expose the sampling cavity 110 to tissue at thebiopsy site. A firing mechanism 124 is engaged to the proximal ends 84,108 of the coring cannula 68 and the wire 76, respectively and isoperable to move the coring cannula 68 relative to the wire 76 from thesecond position to the first position to trap tissue from the biopsysite in the sampling cavity 110. Any suitable firing mechanism iscontemplated. In a preferred embodiment, the firing mechanism is asingle action biopsy mechanism as shown in FIG. 15 and which is marketedby U.S. Biopsy, a division of Promex, Inc., Franklin, Ind.

Referring again to FIGS. 5 and 15, biopsy device 52 is provided withfiring mechanism 124, which includes housing 128 having finger grips 130and 132. An actuator 134 is operatively engaged to both the wire 76 andthe coring cannula 68. The actuator 134 includes a gripping portion 136and a drive mechanism 138. The drive mechanism 138 operates to depress adrive carriage 140 against the action of a spring 142. The housing 128includes a resilient latch 144 that engages an underside 146 of thecarriage 140 in the retracted position. The latch 144 is released byforward movement of the drive mechanism 138 so that the spring 142pushes the carriage 140 outwardly which in turn thrusts cannula 76 overthe sampling cavity 110 of the wire 76. Cover 148 snap-fits over housing128 to protect spring 142 and the sliding engagement between carriage140 and housing 128 from debris and interference. A suitable firingmechanism is disclosed in U.S. Pat. No. 6,056,760 filed Oct. 13, 1998.Firing mechanism 124 propels coring cannula 68 over wire 76 to traptissue within sampling cavity 110 in wire 76. Although single actionbiopsy devices are effectively used to obtain tissue samples, doubleaction firing devices, such as the device disclosed in U.S. Pat. No.5,538,010 to Darr and Ireland may be used in place of the single actiondevice.

In a preferred embodiment and as best seen in FIGS. 14 and 16, coringcannula 68 is fixed to drive carriage 140 such that discrete slots 92,94 and coring relief notch 88 include their respective openings facingthe underside 146 of drive carriage 140. Further, wire 76 is positionedon actuator 134 such that wire relief notch 112 is opposingly facedrelative to underside 150 of firing mechanism housing 128. When firingmechanism 124 is assembled, wire relief notch 112 in wire 76 superposescoring relief notch 88 in coring cannula 68 and discrete slots 92, 94 incoring cannula 68 face underside 150 of firing mechanism housing 128.

Coring cannula 68 and wire 76 traverse curve 42 in introducer 34, suchthat discrete slots 92, 94 in cannula 68 are axially aligned relative toinner radius 152 of curve 42. Inner radius 152 of curve 42 is located onreference axis Y (FIGS. 10–13). Flexible portions 96, 98 of cannula wall82 provide the greatest degree of flexibility when discrete slots 92, 94are circumferentially aligned with inner radius 152. Additionally,cannula 68 and wire 76 is most flexible traversing curve 42 inintroducer when flexible wall portion 120 of wire 76, adjacentlypositioned relative to gap 122, overlays inner radius 152 of curve 42.To ensure cannula 68 and wire 76 is preferably inserted into introducer34, flange 154 of introducer 34 preferably includes arrow-shaped portion156 which aligns with underside 150 of firing mechanism 124 as shownFIG. 18.

In preparation for activating firing device 124, tip 38 of introducer 34is ideally located in the hepatic vein and the cannula 68 and wire 76are advanced into the proximal end 56 of the introducer 34. Preferably,underside 150 of firing mechanism 124 is circumferentially aligned witharrow shaped portion 156 of flange 154 and cannula 68 and wire 76 areadvanced through introducer 34. Once underside 150 of firing mechanism124 is aligned relative to arrow-shaped portion 156 of flange 154 andthe cannula 68 and wire 76 are fully advanced within introducer 34, thefiring mechanism 124 is poised for firing. Alternatively, similarresults may be achieved if cannula and wire, 68, 76, are rotated 180□such that underside 150 of firing device 124 is circumferentially offset180□ relative to arrow shaped portion 156 of flange 154, as illustratedin FIG. 5. In this configuration discrete slots 92 and 94 in cannula 68are circumferentially aligned with outer radius 158 of curve 42 inintroducer 34. Consequently, as slots 92, 94 traverse curve 42 they tendto spread apart at outer surface 102 of cannula 68 rather than pinchtogether as illustrated in FIG. 14.

A second embodiment biopsy device according to the present invention isillustrated in FIGS. 19 and 20. Certain elements are indicated by primedreference numerals which indicate that the element has been modifiedrelative to the corresponding element of the first embodiment. Biopsydevice 52′ includes cannula 68′ and wire 76′ operably engaged withfiring device 124. In contrast to wire 76 of the first embodiment biopsydevice 52 (FIGS. 7–9), wire 76′ of second embodiment biopsy device 52′includes distal end 80′ provided with a pair of discrete slots 160, 162.Each slot 160, 162 extends radially into surface 164 of wire 76′,leaving respective semi-circular portions or flexing portions 168, 170respectively positioned at the bottom of their respective slots. As tip114′ of wire 76′ traverses curve 42 in introducer 34, each slot 160, 162allows wire 76′ to temporarily flex, significantly reducing slidingresistance between outer surface 102′ of cannula 68′ and inner surface46 of introducer 34. Further, flexing portions 168, 170 are sized toallow flexibility in cannula 68′ yet enough material is left such thatpermanent deformation of wire 76′ is avoided. Each slot 160, 162 allowswire 76′ to flex as it passes over outer radius 158 (FIGS. 12, 14 and15) of curve 42 in introducer 34 to relieve resistance between cannula68′ and inside surface 46 of introducer 34 when cannula 68′ and wire 76′are advanced toward flange 154 of introducer 34.

Wire 76′ includes wire relief notch 172 which acts to decreaseresistance between wire 76′ and cannula 68′ during firing of firingmechanism 124. Relief 172 also acts as a sampling cavity for livertissue to be captured therein as wire 76′ is advanced into the liver aspreviously described. Cannula 68′, as illustrated in FIGS. 19 and 20, isa continuous cannula however it is envisioned that similar discreteslots (not shown), such as slots 92, 94 within cannula 68 of biopsydevice 52 (FIGS. 8 and 9), may be provided in cannula 68′ of biopsydevice 52′ to further decrease resistance at curve 42 of introducer 34.

In operation, the transvenous or transjugular liver biopsy procedureinvolves inserting the introducer cannula 34, which is a long, smalldiameter tube, into the internal jugular vein in the neck and isradiologically guided through a tortuous path of veins which lead to theliver, a distance of approximately 60 cm. Once the introducer 34 ispositioned just outside of the liver, the cannula 68 and wire 76 areinserted through the lumen 36 and are then advanced directly into theliver to obtain a sample of tissue.

The introducer 34 is inserted into an incision made in the patient'sjugular vein (FIG. 21) with the patient under local anesthetic. With thepatient supine and positioned on a moveable table, the table is tilted afew degrees to distend the internal jugular and decrease the risk of airembolism. Referring to FIG. 21, the introducer is advanced along theinferior vena cava and into the right atrium. Positioning of theintroducer is achieved through, for example, fluoroscopic X-ray or otherimaging technique, as is customary. Tip 38 of introducer 34 includes aradio opaque marker (not shown) impregnated into a flexible outer sheath75 to assist the surgeon in guiding the introducer to its target. Stillwithin the inferior vena cava, the tip 38 of introducer 34 (FIG. 4) iscarefully advanced through the inferior vena cava and positioned justabove the level of the hepatic vein. The right or middle hepatic vein,if the introducer was placed in the patient's right jugular vein, forexample, is then selected and the introducer tip 38 is advanced wellinto the liver through the hepatic vein. Occasionally, significantresistance is encountered when attempting to advance the introducer intothe hepatic vein due to the confluence formed between the horizontallyorientated hepatic vein and vertically oriented inferior vena cava.Introducer 34 includes the significant curve 42 located near its tip 38to assist in traversing this confluence without significant difficulty.

During placement of the introducer, and once placement is achieved,further movement of the introducer is avoided to prevent damage to liverparenchyma, and in extreme instances, perforation of the liver capsule.Even slight movement of the introducer is avoided since the biopsyspecimen is likely to be adversely affected if the introducer isdislodged from its ideal placement.

The present invention provides biopsy devices that are flexible yet selfsupporting for insertion into introducers. The flexible regions of thebiopsy devices avoid binding and galling. This results in an improvementin the quality of the samples and durability of the devices. Moreover,the devices are not directional and they can be rotated within theintroducer lumen to traverse curves within the introducer lumen.Although the devices of the present invention are remarkably flexible,the strength, durability and function of the assembly are notcompromised.

While this invention has been described as having exemplary designs, thepresent invention can be further modified within the spirit and scope ofthis disclosure. This application is therefore intended to cover anyvariations, uses, or adaptations of the invention using its generalprinciples. Further, this application is intended to cover suchdepartures from the present disclosure as come within known or customarypractice in the art to which this invention pertains and which fallwithin the limits of the appended claims.

1. A medical access assembly, comprising: an elongated introducercannula defining an introducer lumen having a curved portion; a set ofneedles adapted to be disposed within said introducer lumen andincluding a hollow outer needle having a wall defining a lumen and afirst relief notch having a length along a longitudinal axis of saidhollow outer needle, said length of said first relief notch longer thana width of said first relief notch, an inner needle disposed within saidlumen of said outer needle and defining a second relief notch having alength along a longitudinal axis of said inner needle, said length ofsaid second relief notch longer than a width of said second reliefnotch, said inner needle and said outer needle having a first positionwith said inner needle retracted within said lumen of said outer needlewith said first relief notch superposed over said second relief notch;and said outer needle and said inner needle being sufficiently flexiblewhere said first relief notch is superposed over said second reliefnotch to traverse said curved portion without binding between theneedles as said needle set is inserted into said introducer lumen. 2.The medical access assembly of claim 1 wherein said outer needle furtherdefines a slot.
 3. The medical access assembly of claim 2 wherein saidslot is between a distal end and said first relief notch.
 4. The medicalaccess assembly of claim 2 wherein said first relief notch is axiallyaligned with said slot.
 5. The medical access assembly of claim 2wherein said outer needle further defines a second slot adjacent adistal end.
 6. The medical access assembly of claim 1 wherein said innerneedle defines a sampling cavity adjacent a distal end of said innerneedle, said outer needle covering said sampling cavity in the firstposition, the set of needles movable between the first position and asecond position wherein said distal end of said inner needle is extendedaway from said outer needle to expose said sampling cavity.
 7. Themedical access assembly of claim 6 wherein said sampling cavity isaxially aligned with said second relief notch.
 8. The medical accessassembly of claim 6, further comprising a firing mechanism engaged toproximal ends of said outer hollow needle and said inner needle, saidfiring mechanism operable to move said outer hollow needle relative tosaid inner needle from the second position to the first position to traptissue in the sampling cavity.
 9. A set of needles, comprising: a hollowouter needle having a wall defining a lumen and a first relief notchhaving a length along a longitudinal axis of said outer needle, saidlength of said first relief notch longer than a width of said firstrelief notch; and an inner needle slidably disposed within said lumen ofsaid outer needle and defining a second relief notch having a lengthalong a longitudinal axis of said inner needle; said length of saidsecond relief notch longer than a width of said second relief notch;said inner needle and said outer needle having a first position withsaid inner needle retracted within said lumen with said first reliefnotch superposed over said second relief notch, wherein said innerneedle defines a sampling cavity adjacent a distal end of said innerneedle, said outer needle covering said sampling cavity in the firstposition, the set of needles movable between the first position and asecond position wherein said distal end of said inner needle is extendedaway from said outer needle to expose said sampling cavity.
 10. The setof needles of claim 9, further comprising a firing mechanism engaged toproximal ends of said outer hollow needle and said inner needle, saidfiring mechanism operable to move said outer hollow needle relative tosaid inner needle from the second position to the first position to traptissue in the sampling cavity.
 11. The set of needles of claim 9 whereinsaid outer needle further defines a slot.
 12. The set of needles ofclaim 11 wherein said slot is between a distal end of said outer needleand said first relief notch.
 13. The set of needles of claim 11 whereinsaid first relief notch is axially aligned with said slot.
 14. The setof needles of claim 11 wherein said outer needle further defines asecond slot adjacent said slot.
 15. The set of needles of claim 9wherein said sampling cavity is axially aligned with said second reliefnotch.